Modern hearing aids include a Digital Signal Processor (DSP). This integrated circuit is especially designed for audio processing purposes. It is not arranged with many features to perform non-audio tasks. RIC modules have a built in identification. The DSP can recognize the correct RIC module by reading a resistor value inside the RIC module.
The DSP of a hearing aid is not suitable for reading sensors and processing the measurement data. Nowadays many sensors are available which could be used in a hearing aid to make the hearing aid more intelligent. Also the DSP of a hearing aid is busy with audio processing. However, it is difficult to let the DSP perform other tasks than the normal audio processing, such as dealing with a complex user interface. Another problem is the power consumption of the DSP. It would be advantageous for battery life to turn off the DSP in periods in which there is no need for audio processing. This is however only possible if some intelligent part in the hearing aid monitors the state of the hearing aid and its surroundings to determine whether the DSP has to be turned on again. At this moment the DSP does not support that kind of functionality.
Identification of a RIC module by the DSP is done by reading a resistor value. At current date it is getting more and more difficult to find a resistor value which is not yet in use and assigned to a certain type of RiC-module. A hearing aid consumes a lot of energy. Battery life is short. The DSP will not go in low power mode or off mode when no audio processing is needed.